Bulbophyllum barbatum Barbosa Rodrigues (1882: 119)

Menezes, Euler L. F., Giordani, Samuel C. O., Rosim, Mauro S. & Gonella, Paulo M., 2022, Over a century later and 400 kilometers apart: rediscovery of Bulbophyllum barbatum (Orchidaceae) in Diamantina, Minas Gerais, Brazil, Phytotaxa 536 (2), pp. 175-182 : 176-180

Bulbophyllum barbatum Barbosa Rodrigues (1882: 119) .— Figures 1–3

Type:— BRAZIL. MINAS GERAIS: Parahybuna, Serra das Bicas, 18 May 1879, J. Barbosa Rodrigues s.n. (lost). Lectotype (designated by Smidt & Borba 2009a: 634): Barbosa Rodrigues’ original drawing which appeared in his unpublished work “ Iconographie des Orchideés du Brésil 5: t. 251 fig. b”, deposited in the library of Jardim Botânico do Rio de Janeiro and reproduced in Sprunger et al. (1996, v.1, t.377, fig. b.).

Description: — Herbs small, epiphyte or occasionally rupicolous. Roots c. 0.5 mm in diameter, slender, fasciculate. Rhizome 3–4 mm long, cylindrical, reptant, inconspicuous, brownish. Pseudobulbs 11–14 mm at the largest diameter and 7–9 mm at the smallest, ovoid, compressed, coated with a very fine senescent bract, dark green, smooth and shiny when young, then yellowish-green, rugose and opaque, unifoliate. Leaves 20–24 × 12–14 mm, ovate to elliptical, plane, glabrous, smooth, coriaceous, with salient midrib on the abaxial face and forming a longitudinal groove on the adaxial face, base constricted, apex acute, margins entire and slightly revolute, grayish-green when young, then yellowish-green. Inflorescence a raceme; scape 100–150 mm long, 0.8–1.0 mm in diameter, cylindrical, thin, green tinged with purple, presenting 4 to 8 nodes with sterile bracts; sterile bracts 0.8–1.0 × c. 1 mm, amplexicaul, margins entire, brownish; rachis 40–60 mm long, thin, semi-upright to pendulous, 10–14 flowers arranged distichously, anthesis simultaneous; floral bracts 1.7 × 0.8 mm, patent, triangular, sepaloid, apex acute, margin entire, completely covering the pedicel+ovary and part of the dorsal sepal, purplish with vinaceous mid vein. Flowers pendent, membranaceous, jugae present, inconspicuous. Pedicel and ovary 1.3 × 1.2 mm, cylindrical, glabrous, brown, ovary obscure. Sepals navicular, trinerved, yellowish-green with longitudinal vinaceous spots, margins ciliated, trichomes linear, short, purple; dorsal sepal 5–6 × 2.1–2.2 mm, triangular, apex acute; lateral sepals 5–6 × 2.4–2.6 mm, free, triangular, slightly falcate, apex acute. Petals 1.4–1.5 × 0.4–0.5 mm, inconspicuous, sessile, lanceolate to obovate, apex obtuse, veins inconspicuous, parallel to column, translucent white with minute vinaceous spots at base, margins ciliated, trichomes 0.9–1.1 mm long. Lip 4.8–4.9 × 1.7–1.8 mm, entire, yellowish-green with vinaceous stains, unguiculated, flat, linear-lanceolate, apex obtuse, with a longitudinal groove in the center which widens and deepens towards the base, margins densely ciliated, trichomes linear, dark purple, 0.1 mm long at the base progressively longer towards the apex reaching up to 2 mm. Column short, 2 × 1.5 mm, rhomboid, concave, glabrous, milky white with vinaceous spots on the back, with two dentiform stellids larger than the anther; column foot short, c. 0.4 mm long; stigmatic cavity large, oval; anther cuculiform, base circular, apex acute and deflexed, yellow at the base and green at the apex, ciliated at the base near to the stigmatic cavity, trichomes linear; pollinia 4, overlapping, monomorphic, yellow. Fruit not seen.

Specimens examined: — BRAZIL, Minas Gerais: Diamantina , 31 March 2020, fl., E.L.F. Menezes & S.C.O. Giordani 206 (HDJF 7058) ; ibid, 05 April 2020, fl., E.L.F. Menezes 223 (HDJF 7891) ; ibid, 29 March 2021, fl., E.L.F. Menezes & S.C.O. Giordani 492 (BHCB 205936) .

Distribution and habitat: —The species was originally described based on material collected near Parahybuna, current Juiz de Fora, in southern Minas Gerais ( Fig. 1 ), a region known as “Zona da Mata Mineira” due to its original forest cover (seasonal semideciduous forest), inserted in the Atlantic Rainforest domain. The protologue further adds “growing in the forests of Serra das Bicas, 608 meters above sea level” ( Barbosa Rodrigues 1882). The “Serra das Bicas” likely refers to the current municipalities of Bicas or Maripá de Minas, east of Juiz de Fora. The habit is not mentioned in the protologue, but the species was assumed to be epiphyte ( Smidt 2020).

The new populations were found in the municipality of Diamantina , over 400 km to the northwest of the type location ( Fig. 1 ), in small fragments of gallery forest (“capões de mata”) inserted in the campos rupestres vegetation at elevations from 1050 m to 1270 m. These new subpopulations were found only two kilometers apart and, while in one population all individuals were observed growing as epiphytes over unidentified tree hosts ( Fig. 3C, D ), in the other all individuals were growing as rupicolous ( Fig. 3A, B, E ) in quartzitic rock shaded by the surrounding trees. At both sites, the species was found syntopic with other Orchidaceae species, including two other Bulbophyllum species , B. carassense Mota et al. (2009: 381 ; Fig. 3E ), and B. plumosum ( Barbosa Rodrigues 1877: 44) Cogniaux (1902: 614) None of these populations are within Protected Areas.

Phenology:— Barbosa Rodrigues (1882) reports flowering in May, while in the new records flowering was observed earlier, in March and April.

Preliminary conservation status: —Critically Endangered—CR B2ab(iii). Bulbophyllum barbatum is likely to be extinct at the type location since it was not recollected in the region in the past 139 years. Similar to other regions of the Atlantic Rainforest, the region around the town of Juiz de Fora suffered from intense deforestation in the last centuries, with the conversion of the original forests into pastures and agricultural lands. The new populations were found in small montane forest fragments isolated among grasslands and rock outcrops of the campos rupestres, therefore a naturally fragmented habitat. Both new areas were used in the past for diamond panning and are currently not protected, lying close to the town of Diamantina and touristic attractions such as waterfalls, being susceptible to frequent anthropogenic fires. Only around 40 mature individuals were observed at each of the new subpopulations, which also makes the species susceptible to poaching and over-collection.

Taxonomic comments: — Bulbophyllum barbatum was placed in B. sect. Xiphizusa ( Reichenbach 1852: 919) Cogniaux (1902: 607) by Smidt (2007) based on the similar vegetative morphology to other species of the section (e.g. small discoid pseudobulbs, that are aggregated and unifoliate; Figs. 2A , 3A ). This section is a monophyletic group comprising 23 Neotropical species, centered in the campos rupestres of the mountains of east Brazil (Smidt et al. 2007, 2011). Besides the aforementioned vegetative characteristics, the group is characterized by long scape with flowers arranged distichously in a thin rachis; lateral sepals usually united to form a synsepal ( B. barbatum being one of the few exceptions); petals erect, with margins pilose; lip trilobed (the only exception being B. barbatum with lip entire); column foot with entire apex, shorter than column length (Smidt & Borba 2009; Smidt et al. 2011).

The species is distinct from all other species of the section by the unique floral morphology, with sepals and petals with pilose margins ( Fig. 2F, H ), anther base pilose ( Fig. 2H, I ), petals lanceolate to obovate, and lip entire, densely pilose along the margin ( Fig. 2C, G ).

Although the lectotype of B. barbatum is an illustration rather than a specimen, it is not necessary to designate an epitype as the original illustration by Barbosa Rodrigues is very detailed and unambiguous, therefore not meeting the requirements of Article 9.9 of the Code ( Turland et al. 2018) for the designation of an epitype.

Figures

FIGURE 1. Distribution map of Bulbophyllum barbatum in Minas Gerais, SE Brazil.

FIGURE 2. Bulbophyllum barbatum. A, habit. B, flower in front view with retracted lip. C, flower in front view with distended lip. D, flower in lateral view with floral bract. E, flower in dorsal view with floral bract. F, sepals in adaxial view, dorsal (left) and lateral (the two on the right). G, lip in adaxial view. H, dissected flower with sepals and lip removed, showing columns and petals in ventral (left) and dorsal (right) views. I, dissected flower with all sepals and petals removed, showing column in lateral view.

FIGURE 3. Bulbophyllum barbatum in situ showing rupicolous growth (A, B, E) and epiphytic (C, D). A, vegetative organs. B, flowering individual. C, large epiphytic individual. D, inflorescence. E, individual of B. barbatum (right) growing syntopic with B. carassence (indicated by arrow).